1. Field of the Invention
The present invention relates generally to a magnetic transducer head, and is directed more particularly to a reproduction magnetic transducer head which utilizes a magneto-resistance effect element whose electrical resistance varies in response to a magnetic field applied thereto.
2. Description of the Prior Art
In the art, it is known that a magneto-resistance effect type magnetic transducer head is high in sensitivity upon a narrow track reproduction, a short-wave reproduction and an extremely low speed reproduction as compared with an ordinary electro-magnetic induction type reproduction magnetic transducer head.
As the magneto-resistance effect type magnetic transducer head, there are proposed various type of heads dependent upon the arrangement of magneto-resistance effect elements (which will be hereinafter referred to simply as MRE elements) and bias applied thereto.
FIG. 1 is a perspective view showing a fundamental example of the MRE type reproduction magnetic transducer head of a so-called perpendicular type which is used to read out the recorded signal on a magnetic record medium such as a magnetic tape 1 in accordance with the magnetic field component in the direction perpendicular to the surface direction of the magnetic layer on the tape 1 which is magnetized. In this case, an MRE element 2 which is formed to be a thin film is located along the width direction of magnetic tape 1 and the film surface of MRE element 2 is located perpendicular to the surface of magnetic tape 1. Terminals 3a and 3b are led out from both ends of MRE element 2, and, for example, a series connection of a DC power source S and a resistor R is inserted between terminals 3a and 3b so as to cause a current I to flow through MRE element 2. Output terminals t are led out from the both ends of resistor R. The magnetic tape 1 is transported in its longitudinal direction as indicated by an arrow a relative to the MRE element 2 and the signal recorded on the magnetic tape 1 is reproduced by the head or MRE element 2 in such a manner that the resistance variation of MRE element 2 caused by the recorded magnetic field (signal) on magnetic tape 2, especially its perpendicular magnetic field component is detected as a voltage variation across the resistor R.
FIG. 2 is a perspective view showing a fundamental construction of a horizontal type MRE reproduction type magnetic transducer head which reads out the recorded signal on the magnetic tape 1 by detecting the magnetic field component in the direction parallel to the surface of the magnetic layer of magnetic tape 1. In FIG. 2, reference numerals and letters which are the same as those in FIG. 1, designate the same elements, and their description will be omitted for the sake of brevity.
In the prior art examples of FIGS. 1 and 2, the MRE element 2 is directly located in the recorded magnetic field of magnetic tape 1. It is, however, possible as shown in FIG. 3, that a magnetic core 4, which is made of a soft magnetic material and has an air gap g at its lower side, is provided and the MRE element 2 is located at an air gap G provided at the upper side of magnetic core 4.
It is also possible that magnetic shield bodies 5 are disposed at both sides of MRE element 2 similar to that of FIG. 1, as shown in FIG. 4.
Further, it is possible to take such a configuration that a bias magnetic field is applied to an MRE element 2. For example, as shown in FIG. 5, an electrically conductive body 6 is located along the MRE element 2 and a current Ib is flowed through the conductive body 6 to generate a bias magnetic field to be of a current bias construction.
It is also possible that, as shown in FIG. 6, a permanent magnet 7 is located in opposed relation to the MRE element 2 to apply a bias magnetic field to the latter.
As set forth above, various constructions of MRE element type reproduction magnetic transducer heads are proposed in the art. However, since the MRE element itself is great in temperature dependency, it is apt to be affected by external circumferential temperature changes such as an external temperature source and hence thermal noise is easily generated. Further, no MRE element which is sufficiently good in linearity is proposed yet.